Rhodotus palmatus (Basidiomycetes, Agaricales, Tricholomataceae) in Illinois

Abstract

Although widespread, Rhodotus palmatus is considered by some to be rare in the United States. Previous reports for Illinois noted its occurrence in only two northern counties - Cook and Henry - and two adjacent central Illinois counties - Champaign and McLean. However, recent collections made by us and a survey of additional herbarium material from other parts of the state support a broader distribution pattern. New records include specimens from Coles, Hancock, Jackson, Jo Daviess, Knox, Moultrie, Shelby, Vermilion, and Warren Counties. Within Illinois, Rhodotus palmatus is not found with frequency during any one collecting season. Morphological and most anatomical features of Illinois material agree with previous descriptions. Contrary to Singer's circumscription, cheilocystidia were often abundant. The degree of gelatinization in the pileus trama appeared related to cell depth within the tissue; elements further removed from the surface were less gelatinized. This variation in gelatinization was less evident in the lamellar trama. The documented fruiting period in Illinois extends from May through October, with no records for July.